Solenoidal thin film read/write head for computer mass storage device and method of making same

ABSTRACT

A new read/write head for use in a mass storage device in a digital data processing system. The head is a thin-film head having a solenoidal coil around one or both of the pole pieces. Sets of planar conductive traces are formed on planar layers of insulating material on opposing sides of a pole piece, with vias connecting the ends of selected traces to thereby form a solenoidal coil around the pole piece.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

U.S. patent application Ser. No. 894,784, filed Aug. 8, 1986, nowabandoned, in the name of Shyam Chandra Das, for MicrolithographicTechnique Using Laser For Fabrication of Electronic Components And TheLike, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to the field of read/write heads for usein mass storage devices for digital data processing systems, and moreparticularly to such heads manufactured by thin film techniques. Theinvention provides a new thin film head which incorporates a solenoidalenergizing coil, and a method of fabricating the new head.

2. Description of the Prior Art

A typical modern digital data processing system comprises a hierarchy ofmemory devices, including a semiconductor main memory of relativelysmall capacity, and one or more mass storage devices, which have muchgreater capacity than the main memory, but which are also relativelymuch slower. The mass storage devices provide a back-up store for datawhich is in the main memory, and also for the voluminous amounts of datawhich will not fit into main memory but which can be called upon by theprocessor when it is needed. A processor typically only obtainsinformation directly from the main memory, and so, when it needsinformation which is only in a mass storage device, it enables the massstorage device to copy the information to the main memory. Some timelater, after it has processed the information, the processor enables theprocessed information to be stored in the mass storage device. Thisfrees up storage in the main memory so that other information may bestored there.

Typical mass storage devices store information on magnetic disks, theinformation being recorded in the form of transitions in magnetic fluxin the magnetic media generated by a read/write head. The information isorganized into a plurality of tracks, each a selected radial distancefrom the center of the disk, and each track is divided into a pluralityof sectors, with each sector subtending a predetermined angular portionof the disk. The read/write head is suspended from an arm, which ismoved generally radially over the disk surface in a "seek" operation tobring the read/write head into registration with a selected disk track.The disk is rotated in a "search" operation to bring the sectorcontaining the desired information into angular registration with theread/write head, which reads the information contained in the sector, orwrites information on the magnetic medium in the sector.

Originally, read/write heads were generally toroidal in shape with a cutor gap, with the ends of the toroid at the gap being pole pieces. A wirecoil was wound around the toroid and is energized to generate magneticflux. The flux diverges between the pole pieces and impinges on themagnetic material of the disk. The density with which data may bewritten is directly related to the number of flux transitions, orchanges in flux direction, which the heads may provide per unit of time.Since these heads have a relatively high electrical inductance, toachieve a satisfactory rate of flux transitions, expensive drivingcircuitry is required. Furthermore, the high inductance results inincreased "ringing", in which a signal, at a sharp transition, tends tofluctuate about the desired signal level. Too much ringing leads touncertainty in the signal level for too long a time, which requiresslowing down the system.

More recently, thin film read/write heads have been developed which havemuch lower inductance than conventional read/write heads. Thin filmread/write heads are fabricated by means of lithographic techniques thatare generally similar to the techniques that are used in makingintegrated circuit chips. In such techniques, a planar pole piece isfirst formed and covered with an insulating material. A coil is thenformed on the insulating material in the shape of a planar spiral overpart of the pole piece, an insulating material is deposited over thespiral, and another pole piece is formed on top of the insulatingmaterial.

However, because the coil of a typical thin film read/write head has aplanar spiral shape, a relatively long conductor is required to providethe number of turns in the coil that is required to generate the desiredmagnetic field during the write operation, or to intercept the magneticfield sensed by the head during a read operation. Since, in a planarspiral, the length of the conductor increases faster than the number ofturns, the long spiral conductor results in a relatively largeresistance, which, in turn, results in generation of a significantamount of heat. The increase in the resistance of the coil also resultsin a concomitant increase in the noise of the signal during the readingoperation.

Furthermore, when the coil has a spiral shape, the mutual inductancebetween turns also increases faster than the number of turns, and so aplanar coil having a sufficient number of turns also has a relativelyhigh inductance. The high inductance results in a relatively loweffective resonant frequency, which, in turn, increases the amount ofundesirable ringing that can occur in a signal applied to the coil. Inaddition, since the coil has a relatively high inductance, a highdriving voltage is required during a write operation to provide thenecessary write current.

U.S. Pat. No. 3,662,119, entitled Thin Film Magnetic Transducer Head,issued May 9, 1972, to L. Romankiw, et al., discloses a thin film headhaving a solenoidal coil formed around both pole pieces in the head toprovide both a supply and a return path for electrical current whichenergizes the coil. The coil is formed in one layer around each polepiece using a complex fabrication method. Since coil layers are requiredaround both pole pieces, the coil is not suitable for use in connectionwith vertical recording techniques now being developed, in which data isrecorded vertically rather than horizontally on a disk surface.

SUMMARY OF THE INVENTION

The invention provides a new and improved thin film read/write head fora disk storage unit in a digital data processing system, in which theenergizing coil is in the form of a solenoid around at least one of thepole pieces, and a method of fabricating the head.

In brief, the new head includes a pair of planar pole pieces. Asolenoidal coil is formed around at least one of the pole pieces, thesolenoid coil being in the shape of several series of planar traces ofconductive material on opposing sides of the pole piece, spaced apartfrom the pole piece by planar layers of insulating material. The tracesare in a generally skewed direction to the axis of the pole piece. Theends of several of the traces on the opposing sides of the pole pieceoverlay each other and are connected together through vias to form acoil layer effectively forming a continuous circuit with planar tracesinterconnected by vias. When current is applied, a magnetic field isgenerated in the pole piece. After the coil is formed around the onepole piece, the second pole piece may be formed on one side thereof. Theskewing of the traces permits the applied electrical current to have adirection of movement along the axis of the pole piece while travelingaround the pole piece through the traces and vias.

In a refinement, the coil may comprise two layers of traces on each sideof the pole piece to essentially form two layers of coils, an interiorlayer and an exterior layer, around the pole piece. The two coil layerseffectively allow a return path for current applied to the head throughone of the coil layers. The interior coil is formed from traces whichare, on each side of the pole piece, skewed in opposite directions tothe axis from the outer coil layer, with the traces forming the interiorcoil being somewhat shorter than the traces of the outer coil layer andcloser to the pole piece. The ends of the traces forming the interiorcoil also overlay each other and are connected together through vias.The shorter traces result in the formation of a coil which is interiorof the other coil. The outer and inner coils are connected together atone end thereof.

In the method of fabricating the new head, a planar base is first formedand a series of conductive traces are formed thereon in a generallyparallel direction which is skewed with respect to the directionselected for the axis of the pole piece which will be formed later. Thetraces may be formed by known photolithographic methods. A secondinsulating layer is then deposited thereover. If a second coil layer isto be formed, a second layer of traces is formed on the secondinsulating layer skewed in the opposite direction, from the direction ofthe first layer of traces, with respect to the selected direction forthe pole piece axis.

After the second coil layer is formed, a third insulating layer isformed and a pole piece is formed, again by photolithographictechniques. A fourth insulating layer is formed and a third set oftraces is formed, which is associated with the interior coil. The endsof the third layer of traces generally overlay a number of the ends ofthe second layer of traces, and the traces are generally skewed in theopposite direction, with respect to the axis of the pole piece, as thesecond layer of traces. During this process, vias are formed between theends of the second and third sets of traces and conductive material isdeposited in the vias completing the interior coil. The vias may beformed by the method described in the above-referenced U.S. Pat.application Ser. No. 07/205,490, which is a continuation of Ser. No.06/894,784, now U.S. Pat. No. 4,877,480.

After the interior coil is completed, a fifth insulating layer isdeposited and a fourth set of traces is formed which is associated withthe exterior coil. The ends of the fourth set of traces generally overlythe ends of the first set of traces, except for an end which overliesand end of the second set of traces. Vias are formed to the underlyingends and conductive material is deposited therein. This completes theouter coil and the connection to the interior coil.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention is pointed out with particularity in the appended claims.The above and further advantages of this invention may be betterunderstood by referring to the following description taken inconjunction with the accompanying drawings, in which:

FIG. 1A is a view representing a schematic layout of the various tracesand the pole piece forming part of a read/write head constructed inaccordance with this invention,

FIG. 1B is a table that is useful in understanding FIG. 1A; and

FIG. 1C is a schematic side sectional view, taken along axis 1C--1C, ofthe portion of the head illustrated schematically in FIG. 1A.

DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT

With reference to the Figures, a new read/write head 10 constructed inaccordance with the invention includes a pole piece 12 and a pluralityof traces of conductive material formed on layers of insulating materialsuch as hard baked photoresist, silicon dioxide (SiO₂) and alumina (Al₂O₃). The traces are formed at predetermined angles with respect to alongitudinal axis 13 of the pole piece 12 and interconnected byconductive material deposited in vias in the conductive material asdescribed below. The configuration of the conductive traces, that is,their placement and orientation relative to each other and to the polepiece 12, and of the vias, is selected so that they form a solenoidalcoil around the pole piece.

The head 10 includes four layers of conductive traces formed on planarlayers of insulating material, with two layers being disposed under thepole piece 12 and two layers being disposed above pole piece 12. Inparticular, two of the layers of traces comprise a lower, or first,trace layer including three traces 14, 16 and 18 and an upper, orfourth, trace layer also including three traces 20, 22 and 24. As shownin FIG. 1B, the traces 14, 16, and 18 are all depicted in FIG. 1A bymeans of solid lines, with each pair of solid lines representing onetrace. Similarly, the traces 20, 22 and 24 are all depicted in FIG. 1Aby means of dashed lines with each pair of dashed lines representing onetrace.

The other two layers of traces include a second trace layer, comprisingthree traces 26, 28 and 30 situated between the first trace layer andthe pole piece 12, and a third trace layer comprising two traces 32 and34 situated between the fourth (upper) trace layer and the pole piece12. As shown in FIG. 1B, the traces 26, 28 and 30 are all depicted inFIG. 1A by a dashed line having alternating long and short dashes, andtraces 32 and 34 are depicted in FIG. 1A by a dashed line havingalternating one long and two short dashes.

As shown in FIG. 1C, the pole piece 12 and all of the traces are formedon and embedded in layers of insulating material. Six layers ofinsulating material are depicted in FIG. 1C, namely, layers 36, 38, 40,42, 44 and 46. As explained below in greater detail, after insulatinglayer 36 and traces 14, 16 and 18 are formed, the sequential insulatinglayers 38, 40, 42, and 44 are deposited and the respective traces orpole piece 12 are formed thereon. The ends of the traces of the varioustrace layers are connected together appropriately, as described below,to form a soleniodal coil. In particular, ends of selected pairs oftraces overly each other, and the overlying ends are connected togetherthrough the vias. After the upper trace layer, that is, traces 20, 22and 24, has been formed, and all of the connections through the viashave been formed, an insulating layer 46 is applied thereto to cover thetraces. Thereafter, a second pole piece (not shown) may be formed on thehead 10 as appropriate.

As has been mentioned, the traces are interconnected by appropriate viaswhich are formed through the insulating layers between the ends of thetraces. These interconnections are such as to form a continuous circuit,with the traces and vias cooperating to effectively form a coiledelectrical path around pole piece 12 from the upper end (as shown inFIG. 1) to the tip 74. One such via, namely via 48, connects the rightend (as shown in FIG. 1A) of trace 14 in the lower trace layer, to theright end of trace 24 in the upper trace layer. Similarly, vias 50 and52 interconnect the respective right ends of the other traces 16 and 22,and 18 and 20, in the lower and upper trace layers. Similar vias 54 and56 interconnect the left ends of respective pairs of traces 16 and 24,and 18 and 22, between the first (lowest) and fourth (uppermost) tracelayers. The result is a solenoid coil around pole piece 12 which extendsfrom the leftmost end of trace 14 near the top of pole piece 12 (asshown in FIG. 1A) to the leftmost end of trace 20 near the bottom ofpole piece 12.

The second and third trace layers are similarly interconnected by vias58 (right end of traces 34 and 28), 60 (right end of traces 32 and 26),62 (left end of traces 30 and 34), and 64 (left end of traces 28 and32). This forms a solenoid coil around pole piece 12 which extends fromthe rightmost end of trace 30 near the top of pole piece 12 (as shown inFIG. 1A) to the leftmost end of trace 26 near the bottom of pole piece12. The solenoid coil formed from the second and third trace layers isgenerally interior of the solenoid coil formed from the first and fourthtrace layers.

The two solenoid coils are connected together by a via 66 which connectsthe leftmost end of trace 20, in the upper layer of traces, to theleftmost end of trace 26 in the second layer of traces. The result is asingle solenoid coil having both a supply path and a return path forenergizing current, with both paths being formed around a single polepiece 12. It is apparent that the new head does not require a coil to beformed around the other pole piece to provide a return current path, andso the new head may be particularly useful in connection with verticalrecording methods. However, it is also apparent that another coil may beformed around the second pole piece (not shown) if vertical recording isnot to be used.

Returning to FIG. 1A, the leftmost end of trace 14, and the rightmostend of trace 30 are connected, through vias 74 and 76, to bonding pads70 and 72, respectively, which may be located on, for example, theuppermost (rightmost, as shown in FIG. 1C) surface of insulating layer46. Conventional read/write signal generating and sensing circuitry (notshown) which generates writing current, or senses reading currentgenerated in the head, is connected to the bonding pads in a knownmanner. The bonding pads may be located in any convenient location, butit is desirable that they be formed close to the ends of the traces towhich they connect to minimize the resistance of the path between theline from the read/write signal generating and sensing circuitry.

The method of fabricating the new read/write head is as follows.Initially, the first insulating layer 36 is formed as a base for traces14, 16 and 18, and the traces are formed thereon using any conventionallithographic and metal deposition technique. Then, the second insulatinglayer 38 is formed, using a conventional technique, and the uppersurface (the surface to the right as shown in FIG. 1C) may be smoothed.The upper surface of layer 38 forms the base for traces 26, 28 and 30,which are then formed. The third insulating layer 40 is then formed, andthe pole piece 12 is formed. The pole piece may be formed using similarlithographic techniques, although the pole piece may be somewhat thickerthan the traces.

After the pole piece is formed, the fourth insulating layer 42 is formedand vias are formed to the second layers of traces. A metal layer isthen deposited to form the third layer of traces which also serves tofill the vias with conductive material and thereby form the innersolenoid coil. At the same time, vias, which, as described below, willbe used later to interconnect the first layer of traces and a fourthlayer of traces may be formed and filled with conductive material. Themethod described in the aforementioned U.S. patent application Ser. No.(Attorney's Docket 83-367), entitled Microlithographic Technique UsingLaser For Fabrication Of Electronic Components And The Like, may be usedto form the vias.

After the third layer of traces have been formed and theinterconnections have been formed through the vias between the secondand third layers of traces, the fifth layer of insulating material,layer 44, is formed, and the vias formed to the first layer of traces. Ametal layer is then deposited to form the fourth layer of traces, thatis traces 20, 22 and 24 which also serves to fill the vias conductivematerial to provide the outer solendoid coil. Thereafter, the topinsulating layer 46 is deposited.

The connections between the respective ends of traces 14 and 30 and thebonding pads 70 and 72 may be formed using the same method describedabove of interconnecting the ends of the respective traces. This may bedone at any convenient point in the process.

As has been noted above, a head including a pole piece and conductors asdescribed above constructed in accordance with the invention is usefulin disk drives incorporating either horizontal or vertical recordingtechniques. This is a result of the fact that the solenoid coil formedaround one pole piece, including both the interior and the exterior coillayers, provides both a supply path and a return path for the energizingcurrent. Thus, the head does not require a second coil around the otherpole piece to provide a return current path. Furthermore, the new methodof making the head simplifies fabrication of the head.

It will be appreciated that a read/write head typically includes twopole pieces. In a head which is used in vertical recording, typicallyonly one pole piece will be surrounded by a coil. However, if a head isto be used in longitudinal recording, one or both pole pieces may besurrounded by coils.

The foregoing description has been limited to a specific embodiment ofthis invention. It will be apparent, however, that variations andmodifications may be made to the invention, with the attainment of someor all of the advantages of the invention. Therefore, it is the objectof the appended claims to cover all such variations and modifications ascome within the true spirit and scope of the invention.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:
 1. A method of fabricating a thin film read/writehead for use in a magnetic storage device in a digital data processingsystem, the head being of the kind that includes at least one pole piecehaving a distal end adapted to be disposed adjacent a storage medium anda proximal end opposite thereto, said pole piece defining a longitudinalaxis between said ends, comprising the steps ofA. providing aninsulating substrate; B. depositing a first electrically-conductivetrace portion on said substrate in a first skewed direction with respectto said longitudinal axis; C. depositing a first insulating layer oversaid substrate and said first trace portion; D. disposing the pole pieceon said first insulating layer; E. depositing a second insulating layerover said pole piece and said first insulating layer; F. depositing asecond electrically-conductive trace portion on said second insulatinglayer in a second skewed direction with respect to said longitudinalaxis, said second skewed direction being different than said firstskewed direction; and G. producing vias between ends of traces of saidfirst trace portion and ends of vias of said second trace portion tointerconnect said traces in the form of a pair of serially coupledsolenoids that are each electrically insulated from and disposed aroundsaid pole piece, said solenoids being continuous between a pair of endsadjacent to said proximal end of said pole piece to provide a generallyhelical path for the flow of energizing current around said pole piece,a first one of said solenoids extending from said proximal end of saidpole piece to a region of said distal end of said pole piece, and asecond one of said solenoids returning from said region of said distalend to said proximal end of said pole piece.
 2. The method of claim 1wherein said first and second trace portions each includes a pluralityof traces, said second trace portion being deposited so that an end ofat least one of said traces of said second trace portion overlays an endof a trace of said first trace portion.
 3. The method of claim 1wherein:A. said step of depositing the first trace portion includes thesteps of:i. depositing a first plurality of generally parallelelectrically-conductive traces on said substrate in a first directionskewed with respect to the axis; ii. depositing a layer of insulatingmaterial over said first plurality of traces; and iii. depositing asecond plurality of generally parallel electrically conductive traces onsaid insulating layer in a second direction skewed with respect to saidaxis, the second direction being different from said first direction,the traces of the second plurality of traces having a length that isgenerally shorter than the lengths of the traces of the first pluralityof traces; and B. said step of depositing the second trace portionincludes the steps of:i. depositing a third plurality of generallyparallel electrically-conductive traces on said second insulating layerin a direction skewed with respect to the axis and generally parallel tothe first direction, the traces of the third plurality of traces havinga length similar to the length of the traces of the second plurality oftraces; ii. depositing a layer of insulating material over said thirdplurality of traces; and iii. depositing a fourth plurality of generallyparallel electrically conductive traces on said insulating layer in adirection skewed with respect to the axis and generally parallel to thesecond direction, the traces of the fourth plurality of traces having alength similar to the length of the traces of the first plurality oftraces.
 4. The method of claim 3 wherein an end of at least one of thetraces of the third plurality of traces overlays an end of a trace ofthe second plurality of traces, and an end of at least one of the tracesof the fourth plurality of traces overlays an end of a trace of thefirst plurality of traces, and further that an end of at least one ofthe traces of the fourth plurality of traces overlays an end of a traceof the second plurality of traces, the interconnecting step comprisingelectrically coupling each overlaying end to a respective underlayingend thereby to form said pair of solenoidal coils, a first coilcomprising the traces from the first and fourth plurality of traces andthe second coil comprising the traces from the second and thirdplurality of traces, the first and second coils being serially coupledtogether in said region of said distal end to provide a path for theround trip flow of energizing current from said proximal end to saiddistal end region, and back to said proximal end, all around said polepiece.
 5. The method of claim 1 wherein said vias are produced usinglaser radiation, the first and second trace portions being reflectiveand the first and second insulating layers being non-reflective at thewavelengths of the laser radiation, the step of producing said viascomprisingA. placing a reflective mask over the locations where the viasare to be formed, the mask defining apertures at the locations where thevias are to be formed over the trace portion, B. illuminating the maskwith the laser radiation to remove insulating material exposed by saidapertures to expose selected points of said trace portion, such thatwhen the insulating material exposed by the apertures is removedsufficiently to expose the trace portion, the trace portion stops thelaser radiation, thereby to form recesses; and C. depositing conductivematerial in the recesses.
 6. The method of claim 1 wherein the steps ofdepositing the first insulating layer and the second insulating layereach comprise the step ofdepositing a layer of silicon dioxide.
 7. Themethod of claim 1 wherein the steps of depositing the first insulatinglayer and the second insulating layer each comprise the stepofdepositing a layer of alumina.
 8. The method of claim 1 wherein thesteps of depositing the first insulating layer and the second insulatinglayer each comprise the step offorming a layer of hard bakedphotoresist.
 9. A method of fabricating a head for use in a magneticstorage device, the head being of the kind that includes at least onepole piece disposed along a longitudinal axis and having a distal endadapted to be disposed adjacent to a storage medium of the magneticstorage device, comprising the steps ofdepositing a first set ofelectrically-conductive traces over an insulating substrate at an anglewith respect to the longitudinal axis, depositing a first insulatinglayer over said first set of traces, disposing the pole piece on thefirst insulating layer, depositing a second insulating layer over thepole piece, depositing a second set of electrically-conductive tracesover the second insulating layer at an angle with respect to thelongitudinal axis, and selectively interconnecting traces of the firstand second sets of traces through the first and second insulating layersto form a pair of solenoids that are each electrically insulated fromand disposed around said pole piece, each of said solenoids extendingfrom said proximal end of said pole piece to a region of said distal endof said pole piece, said solenoids being serially coupled together insaid region of said distal end to provide a generally helical path forthe round trip flow of energizing current from said proximal end to saiddistal end region, and back to said proximal end, all around said polepiece.
 10. The method of claim 9 wherein the interconnecting stepcomprises producing vias between ends of the traces of said first andsecond sets of traces.
 11. The method of claim 10 wherein said vias areproduced using laser radiation.
 12. The method of claim 11 whereinA. thestep of depositing the first set of traces comprisesi. depositing afirst plurality of generally parallel electrically conductive traces onsaid substrate in a first direction skewed with respect to thelongitudinal axis, ii. depositing a third layer of insulating materialover said first plurality of traces, and iii. depositing a secondplurality of generally parallel electrically conductive traces on saidthird insulating layer in a second, different direction skewed withrespect to the longitudinal axis; B. the step of depositing the secondset of traces comprisesi. depositing a third plurality of generallyparallel electrically conductive traces on said second insulating layerin the first direction, and aligning ends of the traces of the thirdplurality of traces with ends of the traces of the second plurality oftraces, ii. depositing a fourth layer of insulating material over thethird plurality of traces, and iii. depositing a fourth plurality ofgenerally parallel electrically conductive traces over the fourthinsulating layer in the second direction, aligning ends of the traces ofthe fourth plurality of traces with ends of the traces of the firstplurality of traces, and aligning an end of a trace of the fourthplurality of traces with an end of a trace of the second plurality oftraces; and C. the interconnecting step comprises interconnecting therespective aligned ends of the traces, thereby to form said pair ofserially coupled solenoidal coils disposed around the pole piece, afirst one of said coils comprising traces of the first and fourthplurality of traces and a second one of said coils comprising traces ofthe second and third plurality of traces.
 13. The method of claim 12wherein the interconnecting step comprises producing vias between therespective aligned ends of said traces.
 14. A method of fabricating ahead for use in a magnetic storage device, the head being of the kindthat includes at least one pole piece disposed along a longitudinal axisand having a distal end adapted to be disposed adjacent to a storagemedium of the magnetic storage device, comprising the steps of(a)providing an insulating substrate, (b) depositing a first set ofelectrically-conductive traces over the substrate in a first skeweddirection with respect to the longitudinal axis, (c) depositing a firstinsulating layer over said first set of traces, (d) depositing a secondset of electrically-conductive traces over said first insulating layerin a second, different skewed direction with respect to the longitudinalaxis, (e) depositing a second insulating layer over said second set oftraces, (f) disposing the pole piece on said second insulating layer,(g) depositing a third insulating layer over said pole piece, (h)depositing a third set of electrically-conductive traces over said thirdinsulating layer in the first skewed direction so that ends of traces ofsaid third set of traces overlay ends of traces of said second set oftraces, (i) depositing a fourth insulating layer over said third set oftraces, (j) depositing a fourth set of electrically-conductive tracesover said fourth insulating layer in the second skewed direction so thatends of traces of said fourth set of traces overlay ends of traces ofsaid first set of traces, and an end of one trace of said fourth set oftraces overlays an end of one of the traces of said second set oftraces, and (k) applying laser radiation to produce vias between therespective overlaying ends of said traces and electrically coupling saidrespective overlaying ends through the vias to form a pair of solenoidsaround the pole piece, one of the solenoids comprising the traces of thefirst and fourth sets of traces and the other one of the solenoidscomprising the traces of the second and third sets of traces, each ofsaid solenoids extending from said proximal end of said pole piece to aregion of said distal end, the pair of solenoids being serially coupledtogether in said region of said distal end to provide a path for theround trip flow of energizing current from said proximal end to saiddistal end region, and back to said proximal end, all around said polepiece.
 15. The method of claim 9 wherein said interconnecting comprisesproducing vias between said traces using laser radiation.
 16. The methodof claims 1, 9, or 14 further comprising disposing a second pole pieceadjacent to said at least one pole piece and insulated from said traces.17. The method of claim 16 further comprising electrically coupling aproximal end of said at least one pole piece to a proximal end of saidsecond pole piece.
 18. The method of claim 16 further comprising spacinga distal end of said at least one pole piece close to a distal end ofsaid second pole piece relative to a spacing between said proximal endof said at least one pole piece and said proximal end of said secondpole piece.
 19. A method of fabricating a head for use in a magneticstorage device, the head being of the kind that includes a plurality ofpole pieces, each disposed along a longitudinal axis and having a distalend adapted to be disposed adjacent to a storage medium and a proximalend opposite thereto, comprising the steps ofdepositing a first set ofelectrically-conductive traces over an insulating substrate at an anglewith respect to the longitudinal axis, depositing a first insulatinglayer over said first set of traces, disposing a first one of theplurality of pole pieces on the first insulating layer, depositing asecond insulating layer over said first pole piece, depositing a secondset of electrically-conductive traces over the second insulating layerat an angle with respect to the longitudinal axis, depositing a thirdinsulating layer over said second set of traces, depositing a third setof electrically-conductive traces over the third insulating layer at anangle with respect to the longitudinal axis, depositing a fourthinsulating layer over said third set of traces, disposing a second oneof the plurality of pole pieces on the fourth insulating layer,depositing a fifth insulating layer over said second pole piece,depositing a fourth set of electrically-conductive traces over the fifthinsulating layer at an angle with respect to the longitudinal axis, andselectively interconnecting traces of the first and second sets oftraces and selectively interconnecting traces of the third and fourthsets of traces to form a plurality of solenoids, each of said solenoids:being disposed around one of said pole pieces, having a pair of endsdisposed adjacent to the proximal end of said one pole piece, and beingcontinuous between said ends to provide a generally helical path for theflow of energizing current around said one pole piece, a first portionof each said generally helical path extending from said proximal end toa region of the distal end of said one pole piece, and a second portionof each said generally helical path returning from said region of saiddistal end to said proximal end of said one pole piece.
 20. The methodof claim 11 further comprising electrically coupling said proximal endof said first pole piece to said proximal end of said second pole piece.21. The method of claim 20 further comprising closely spacing saiddistal end of said first pole piece and said distal end of said secondpole piece relative to a spacing between said proximal end of said firstpole piece and said proximal end of said second pole piece.